Then Allie noticed a boy in the middle of the playground who was not playing with the others. He was looking up. She followed his gaze to the skeletal skyscraper across the street. The construction site was filled with activity, with workers welding and hammering on almost every floor.

Allie looked down at her janitorial uniform, to remind herself who she was, then knelt down to the boy.

“What is it?” she said, in a gruff male voice. “What do you see?”

The boy never looked at her. “Nothing,” he said. “Just the building.” And then he added, “It is big, yes?”

Allie recoiled. This was Milos! He must have skinjacked the principal, and was now skinjacking this boy—but he was too absorbed in his mission to notice that the janitor had been skinjacked too. Milos then ran off into the starship, disappearing into the many tunnels . . . and the moment he did, a shadow crossed over the playground.

Allie looked up to see a load of steel beams being raised by a huge sky crane high above the construction site. Allie realized with a sinking feeling that the crane had an arc wide enough to swing out over the playground, if that’s what the crane operator—or the person controlling the crane operator—wanted to do.

“We have to get out!” said Allie. “Everyone! We have to get out of here now!”

But nobody listened. After all, the janitor had little authority over children in a school. Allie quickly leaped out of the janitor and into the teacher closest to the door, and tried to open it. The door wouldn’t budge. Then when she turned toward the side gate, which was the only other way out of the playground, she saw a kid securing it with a bicycle lock, so that no one could get out. This time something about the way he moved allowed her to see right through his disguise.

“Squirrel!” she yelled.

He looked up at her and ran. She knew she had given herself away, but that didn’t matter now. All that mattered was getting those kids out of there. Moose must have already been in the sky crane, because as the massive load of girders rose higher and higher, the crane began a long, slow arc toward the school.

The principal called to the students, not yet realizing what was going on. “Enough playtime,” he told them. “Everyone line up by your teachers.” The kids all grumbled but immediately abandoned the starship until Milos, skinjacking a scrawny blond boy, poked his head out from one of the tunnels.

“Look, everyone! There is money in here.” Then he held out a few dollar bills. “This is why they sent us out here, to find Christmas money!” Suddenly the kids ran happily back to the starship against their principal’s orders.

“I found a dollar!” said one.

“I found five!” said another.